Polarization-multiplexed Cavity Solitons Study In Kerr Resonators

Kerr time cavity soliton is a spatially localized dissipative structure formed by the dual balance of nonlinearity and dispersion,gain and loss of pulsed light in the resonator.It has rich physical connotations and dynamic processes.The application of it to all-optical data acquisition,storage,and processing is highly significant.At the same time,the time cavity soliton shows a new type of spectrum with a comb structure with equally spaced frequencies in the frequency domain and can exist stably.The Kerr optical frequency comb based on the Kerr resonator has a relatively wide wavelength coverage,and the coherence and frequency are stable.Widely employed in lidar,coherent optical communication,optical clock,and other areas,its performance is excellent.A promising application of optical frequency combs is dual-comb spectroscopy.How to output a homologous dual-frequency comb in a fiber resonator based on the idea of polarization multiplexing is a new solution.Although cavity solitons have been extensively studied in the past decade due to their special time-frequency properties,without any additional filtering processing,spectral flatness will be a big limitation in some applications.The large dispersion in traditional optical fibers limits the bandwidth of dual-frequency combs.This paper conducts in-depth research on the generation of broadband coherent flat dual-frequency combs based on fiber resonators.The main achievements are as follows:1)The vector cavity soliton dynamics process in the birefringent fiber ring is studied,and a rotating fusion fiber ring structure(fast and slow axes rotated by 90°dislocation fusion)is proposed to realize polarization decoupling in the asymmetric strong birefringent fiber ring.Theoretical studies show that the generated polarization-decoupled dual-comb power level is close and the repetition frequency difference can be adjusted arbitrarily.In addition,a polarization-maintaining fiber with near-zero flat dispersion is designed,and the designed fiber is applied to a spin-fused fiber resonator to generate a polarization-decoupling broadband dual-frequency comb.The simulation results show that a coherent polarization-decoupled dual optical comb with a 10-dB bandwidth of 33 nm can be obtained.2)The generation and dynamics of cavity solitons in polarized cycled resonators are studied.The polarized cycled cavity solitons show different time-domain/frequency characteristics than traditional cavity solitons.Based on the numerical simulation of the normalized model,we designed a fiber that satisfies the polarization cycle cavity soliton,that is,the group velocities of two orthogonal polarization states at a certain wavelength are equal in value and opposite in sign.Simulation results show that the 3-dB bandwidth and 10-dB bandwidth of the polarization-cycled cavity soliton can be extended to 84 nm and 125 nm,respectively,which is much wider than the bandwidth considering only the anomalous or normal dispersion.This polarization cycle resonator provides a new solution for spectrum broadening.3)The generation and dynamic process of cyclic polarization permutation solitons in a few-mode fiber resonator are studied.By introducing the coupling and exchange between modes,the resonator transforms from a single fundamental mode optical field to a multimode optical field coupled transmission,and the optical field displacement and cross-phase modulation between fundamental and higher order modes generate flat vector solitons.By optimizing the fiber parameters,the group velocities of the fundamental and higher-order modes in the designed few-mode fiber at 1570 nm are equivalent to each other.The numerical simulation results show that the 3 dB and 10 dB bandwidths of this mode multiplexed flat cavity soliton can reach 8 nm and 10 nm,respectively,and the bandwidth and flatness are much greater than those of traditional cavity solitons.